Fire resistant and intumescent laminate, useful as a vapor barrier in wood and steel constructions

ABSTRACT

An intumescent laminate vapor barrier is fabricated with a fire-resistant putty. This has the advantage that it slows down the transmission of heat, expands when being exposed to temperature and thereby seals the cracks which could have been formed during the installation. It also protects the structures (framings) from fire and the sheathing made up of gypsum-boards, plywood, Oriented Strand Boards (OSB) or any other type.

BACKGROUND OF THE INVENTION

It is a known fact that when people use baths, kitchens and sinks inside a house, this generates a significant amount of water vapor. This vapor is retained by the air inside a house, which in turn increases its degree of humidity in relation to the air outside of the house.

Since most construction material is permeable to the passage of water vapor, this humidity penetrates the walls and ceilings to approach the external walls of the buildings, which are generally colder than the interior walls where the steam originates from. This causes the vapor to condensate, which in turn makes contact with the sheathing materials, both structural and insulating, all of which causes serious damage when prolonged in time. Both fiberglass and rock-wool lose their effectiveness when they absorb humidity, loosing their insulating effectiveness. It is for these reasons that contact between the water vapor and the constructive materials at the inside of the house should be avoided, particularly when the construction framings are made of wood. To achieve this, humidity barriers are used. The barrier most commonly used is polyethylene, given its low levels of so-called permeability, or passage of vapor through its structure. For this to be effective, the barrier must be placed on the warmest surface of the structure. In normal conditions, the polyethylene works and protects suitably. However, in case of fire, it even loses its watertightness which can even result in it to start to burn, which only contributes in aggravating the problem. It is known, for example, that when gypsum-boards are used, as is usually the case with wood constructions, these collapse when the temperature surpasses a certain value. It is known that plaster, which is a di-hydrated calcium sulphate, begins to lose the water of hydration at 128° C., and loses it completely at 168° C. When losing the water, a retraction takes place in the plaster which makes is crack and pulverize, thereby losing its mechanical properties which results in the structure collapsing. Once the gypsum board has collapsed, the wood frames are exposed to the fire, and these start to carbonize.

SUMMARY OF THE INVENTION

An intumescent laminate vapor barrier is fabricated with a fire-resistant putty. This has the advantage that it slows down the transmission of heat, expands when being exposed to temperature and thereby seals the cracks which could have been formed during the installation. It also protects the structures (framings) from fire and the sheathing made up of gypsum-boards, plywood, Oriented Strand Boards (OSB) or any other type.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an isometric view, in a partial cut, of a structural wall assembly.

FIG. 2 shows a cross section of a wall assembly, made up of an Oriented Strand Board (OSB) on the outside, and a standard gypsum board on the inside, separated by a wood structure of radiata pine.

FIG. 3 shows a frontal-elevation view of the assembly of FIG. 2, showing the position of four thermal-sensors.

FIG. 4 shows a profile-view of the assembly of FIG. 2, placed in the furnace for fire-resistance testing.

FIG. 5 shows an isometric view of a structural assembly for testing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention comprises producing a membrane or laminate of between 0.2 and 5 mm thickness, and preferably of between 0.5 and 2 millimeters of thickness, by means of a methodology of pressing, laminated in rollers, stretched, or by whatever other means by which to stretch an intumescent inorganic putty, which is self-adhesive and fire-resistant as indicated in the United States Patent Application Publication Number 20070234930 (hereby incorporated by reference in its entirety) or another one, which allows to obtain a laminate, preferably of uniform thickness in all its extension, to be applied as a vapor or humidity barrier in wall assemblies or ceilings with framings made of wood, steel or other materials, whatever the characteristics of their surface.

The thickness of the laminate to be used depends on the fire-resistance required, whereas the dimensions of width and length depend on the project in which it is to be applied.

In one of its forms, and without this limiting the invention to it, this consists of producing a membrane of one millimeter thickness, which is obtained with an amount of about 1400 grams (dry weight) of putty by square meter of laminate, which then reaches a rigid consistency when it is covered by both sides with paper; semi-rigid when it is covered by only one side with paper and flexible for 48 hours, while it remains without being covered, after which it becomes rigid. The superficial coating also can be of other laminated materials, like for example thin fabrics of natural or synthetic fibers, or others.

Another form of producing this invention consists of producing the laminate by impregnating the putty into a fiberglass fabric, or a cloth made with natural synthetic fibers or others, woven or pressed, covered or not with paper on its external faces. Like in the accomplishment of the previous paragraph, the thickness and dimensions depend on the requirements of each application. Just as indicated in the previous paragraph, the impregnated fabrics or cloths can be covered on their surfaces by laminates of paper or other thin laminar materials of any type.

Another form of realizing this invention consists in applying the laminate directly on the surfaces which are to be protected, thereby applying the putty by means of manual or industrial methods.

The adhesion of the laminate to a wood board of any type can also be performed by applying pressure, either by pressed or roller system, in both cold or hot forms, as long as the temperature is less than one hundred degrees Celsius. The temperature can be slightly superior to one hundred degrees Celsius when the substrate to be protected is a fabric or cloth of fiberglass, or when the board is of plaster or fibre-cement.

These laminates, when used like a vapor barrier, allow to solve the problem which current humidity barriers have, namely that in case of fire the current humidity barriers not only do not slow down the propagation the fire, but by being easily combustible products actually aggravate the problem as they tend to burn at very low temperatures.

Another advantage of this invention is the feasibility of depositing or applying the laminate with coating on one side or even without any coating, or laminating it directly on any type of board, like Oriented Strand Board (OSB), plywood board, gypsum board, steel boards, etc., by it being self-adhesive from the moment it is manufactured and for a period of up to two hours after this. If the gypsum board is covered on one side by the fire-retardant putty, and this side faces the interior of the house, then the fire-retardancy effect is further enhanced, since as the transmission of heat is delayed, the temperature of dehydration of the plaster takes much longer to reach, delaying the moment at which the wood frames on the inside of the wall assemblies are directly exposed to the fire.

The use of two laminates, one to each side of the insulating material inside the wall assembly, increases the fire resistance considerably.

EXAMPLES OF APPLICATIONS

This self-adhesive and semi-liquid membrane can be installed to protect a wide array of wood products currently used in construction against fire, such as segments, pillars, T-joists, dividing panels, wall assemblies and fire walls. Is also serves to protect metallic surfaces or structures, doors and elevators. It also increases the fire resistance in gypsum boards, Oriented Strand Boards (OSB), Plywood boards, fibre-cement, fibre-silicate PB, ceilings made of MDF boards, packaging, vehicles, aircraft, etc.

Example 1 Without Insulation

In order to evaluate the usefulness of the self-adhesive intumescent membrane, a fire test was performed of a scaled-down structural wall assembly, namely a 50 by 50 centimeters structure formed by an inner board (11) (exposed to the fire) of a 10 mm width gypsum board, placed on a radiata pine frame (13, 17) of 45 millimeters thickness by 90 millimeters width, covered on the outside by an OSB board (18) of 9.5 millimeters thickness, without any other insulations in between.

In order to determine the effectiveness of the semi-liquid membrane, an additional piece of wood was installed (15) of 45 by 90 millimeters of radiata pine in vertical form in the center of the frame, whereby the laminate of flexible membrane of one millimeter thickness (12) was placed directly behind the gypsum board on one half (11). The other half of the structure was left without the protecting membrane. (FIG. 2 schematically shows the testing frame).

The furnace used for these small-scale tests has an outer dimension of 65 by 65 by 65 centimeters and an interior dimension of 50 by 50 by 50 centimeters. Its thermal insulation is made up of insulating bricks and its heating is achieved by a system of electrical heaters. The temperature sensors of the furnace and the tested assembly are connected to a computerized system of data input, where all the information of the test is registered in real time.

For the test, the assembly was placed with the gypsum board facing the furnace, as seen in FIG. 4. The furnace warmed up according to the standardized curve of temperature-time of ASTM E 119 standard. The test results are indicated in Table 1:

Temperature Temperature Temperature Temperature Temperature Temperature N^(o) 26 of N^(o) 21 of N^(o) 22 of N^(o) 23 of N^(o) 24 of Time ASTM E 119 Furnace protected protected unprotected unprotected (min.) (° C.) (° C.) area (° C.) area (° C.) area (° C,) area (° C.) 0 20 20 17 17 18 18 5 538 595 18 18 21 19 10 704 686 22 21 31 26 15 759 741 28 25 41 37 20 794 786 33 30 54 49 25 821 817 38 35 72 62 30 843 843 45 41 87 76 35 862 864 52 48 100 85 40 878 875 69 58 147 104 45 892 900 96 82 455 192 50 905 923 98 91 55 916 931 99 93 60 927 936 131 100 65 937 954 193 150

By observing the measurement taken during this test, the following conclusions can be made:

Time (min.:seg.) I. OBSERVATION-CONCLUSION 00:00 The test is initiated 36:00 Carbonization occurs in the unprotected area 42:05 Failure criteria is reached in the unprotected area (>180° C.) 46:05 Flames appear in the unprotected area 65:18 Failure criteria is reached in the protected area (>180° C.)

It can be concluded that the use of a membrane of one millimeter thickness, applied directly behind the gypsum board, allows slowing down the time of failure by 23 minutes, which is equivalent to slowing it down by 50% when comparing it to the measurement taken for the area of the unprotected gypsum board.

Example 2 With Insulation

In order to directly visualize the protective effect to the fire of the vapor barrier made with laminates of intumescent, self-adhesive, inorganic fire-resistant putty, a wall assembly as shown in FIG. 5 was constructed for a test, made up of two stiles of radiata pine (28), on to which two laminates (32, 33) of the inorganic intumescent putty of 1.5 millimeters of thickness were placed; the outer side (not exposed to the fire) was covered with an OSB board (29), and the inner side (exposed to the fire) was covered with a gypsum board (30), filling up the interior with fiberglass insulation (31) of 10 centimeters thickness. In the center of this structural assembly, a gas-powered blowtorch/flamethrower was placed at 30 centimeters distance. After a few minutes, the gypsum board disintegrated, exposing the flame directly on to the intumescent inorganic putty laminate, which then lasted for over six hours without any destruction or flame spread.

The numbers indicated in the figures have the following meaning:

-   1. Gypsum board. -   2. Polyethylene vapor-barrier of 0.5 mm thickness. -   3. Wooden stile of 2.5 cm thickness and 5 centimeters width. -   4. Termo-acoustic insulation (fibre-glass) of 2.5 cm thickness. -   5. Phenolic slanting wood-board (plywood) of 1.5 cm thickness. -   6. Radiata pine stile of 5 cm thickness and 10 cm width, placed at     40 cm distances between them. -   7. Thermo-acoustic insulation (fibre-glass) of 5 cm thickness. -   8. Phenolic slanting wood-board (plywood) of 1.5 cm thickness. -   9. Vapor barrier. -   10. Outside cladding. -   11. Gypsum board. -   12. Water-vapor barrier with fire-resistant laminate of inorganic     intumenscent putty. -   13. Radiata pine stile. -   14. Wooden horizontal frame of radiata pine. -   15. Radiata pine stile. -   16. Wooden horizontal frame of radiata pine. -   17. Radiata pine stile. -   18. Oriented Strand Board (OSB). -   19. Area protected by water vapor barrier with fire-resistant     laminate of inorganic intumenscent putty. -   20. Unprotected area. -   21. Position of thermal sensor on testing structure. -   22. Position of thermal sensor on testing structure. -   23. Position of thermal sensor on testing structure. -   24. Position of thermal sensor on testing structure. -   25. Testing furnace. -   26. Position of thermal sensor on testing structure. -   27. Testing structure. -   28. Radiata pine wooden board -   29. Oriented Strand Board (OSB). -   30. Gypsum board. -   31. Fibre-glass insulation. -   32. Water vapor barrier with fire-resistant laminate of inorganic     intumenscent putty.

Chile Priority Application Number 519-07, filed on Feb. 27, 2007 is hereby incorporated by reference in its entirety. 

1. A thin laminate configured as a humidity barrier in wall assemblies and ceilings of constructions of wood, steel or other types, wherein said laminate comprises fire retardant putty, optionally covered by one or two sides with paper or another laminar material of any type, or applied directly without adhesive onto the surface of a gypsum board or another constructive element, without limitations of its type of surface.
 2. The thin laminate as in claim 1, wherein it is covered on one side with paper or other laminar material of any type.
 3. The thin laminate as in claim 1, wherein it is covered on both sides with paper or other laminar material of any type.
 4. The thin laminate as in claim 1, wherein it is not covered on either side.
 5. The thin laminate as in claim 1, wherein it is used on both sides of the insulation material of the wall assemblies.
 6. The thin laminate as in claim 1, wherein it is produced by impregnating the fire-resistant putty into a fiberglass fabric or a cloth made with natural or synthetic fibers or others, woven or pressed, with or without covering on its external faces by paper or any other laminar material of any type.
 7. The thin laminate as in claim 1, wherein the fire-resistant putty laminate attaches or bonds itself onto the surface to be protected, either with or without the use of adhesives, by means of cold presses or hot presses with temperatures less than one hundred degrees Celsius. 